Carlin released Charlie Kimball and Max Chilton’s car numbers for the 2018 Verizon IndyCar Series season last week, and they’re not what you might expect.

Kimball will be in the No. 23 Novo Nordisk Chevrolet and Chilton the No. 59 Gallagher Chevrolet for the Carlin team. They switch from numbers 83 and 8, which they’d run for the entirety of their IndyCar careers thus far.

Neither number has been prevalent on the IndyCar grid in recent years, and hasn’t been utilized since 2011.

Dreyer & Reinbold Racing ran No. 23 for one of its cars from 2008 through 2011, with NBCSN IndyCar analyst Paul Tracy giving the number its most recent start at that year’s Indianapolis 500.

E.J. Viso ran No. 59 in the 2011 season for KV Racing Technology when it still had associated Lotus branding; the team also had No. 82 that year for Tony Kanaan (also with Lotus tie-in) and KV’s more traditional No. 5 for Takuma Sato.

The 2018 season opens in St. Petersburg in March, and returns to NBCSN in April at Phoenix’s renamed ISM Raceway. Carlin is expected to undertake its first tests as an IndyCar team in January, when team testing resumes.